The object of this research project is 1. to develop a human lymphoblastoid cell line with genetic markers that might be utilized for the selection of particular human chromosomes in hybridization experiments, 2. to study the genetic control of phenotypes associated with the immune response (production of immunogloblins, lymphotoxin, etc.,) using these characteristics as non-selective markers in hybridization experiments, 3. to elucidate the mechanism of inhibition of growth of these cells by the natural amino acids and to determine the significance of this inhibition with regard to growth control and transformation, and 4. to study amino acid transport in these cells by utilizing a genetic approach involving the isolation and characterization of amino acid resistant mutants affecting amino acid transport.